Many applications require two or more fluids to be mixed together. For example, two-component adhesives and sealants include a base component and activator component that must be mixed together prior to use. This mixing can be accomplished by forcing each component into and through a motionless (i.e., static) mixer. Such mixers include a mixing component or assembly disposed within a conduit, with the mixing component having a series of interconnected mixing elements in the form of baffles, spirals, wedges, and/or deflection plates. The mixing elements divide and recombine the fluids in an overlapping manner to produce layers of the fluids. Eventually this division and recombination causes the layers to thin and diffuse past one another, resulting in a substantially uniform mixture.
The mixing elements comprised of baffles in conventional static multiflux mixers, examples of which are shown in U.S. Pat. Nos. 6,773,156 and 3,239,197, and plate multiflux mixers, an example of which is shown in U.S. Pat. No. 5,944,419, are oriented in one specific longitudinal direction (relative to the conduit of the mixer) and configured to divide the fluid stream in the same transversal direction (e.g., an X or Y direction). Such an arrangement is desirable because alternating the dividing direction may defeat the purpose of the mixing elements. In particular, when a mixing element that divides in an X-direction and recombines in a Y-direction is immediately followed by a mixing element that divides Y-direction and recombines in the X-direction, the mixing accomplished by the first mixing element may be effectively “undone” by the second mixing element.
One of the challenges associated with the conventional mixing arrangement described above is the elimination of streaks in the extruded mixture. For example, when mixing together fluids of different viscosities, there is a tendency for the low viscosity fluid to channel or “zig-zag” along the interior walls of the conduit instead of being properly included in the layering process. This results in a streak of the unmixed fluid within the extruded mixture dispensed from the static mixer. Such streaks are undesirable for a variety of reasons. They may affect the performance of the product or they may cause the operator of the static mixer to question whether it has effectively mixed the two components or fluids of the adhesive or sealant in cases where the streak does not affect performance.
Several attempts have been made to eliminate streaking by incorporating various additional mixing features, such as webs, varying baffle sizes, and varying baffle geometries, in the series of interconnected mixing elements. However, current technologies leave room for improvement when mixing difficult materials. Streaks still occur with certain materials, requiring the end user to use longer mixers, which are disadvantageous for many reasons. Longer mixers are less manageable to use and generally have a higher retained volume, wasting more fluid when the mixer is disposed. Many elements are designed to be oriented in a specific longitudinal direction when inserted into the conduit of the mixer. Thus, for the fluids to move through the specially designed geometry in the proper direction, the manufacturer must properly orient the mixing elements during assembly of the mixer. Orienting the mixer during assembly adds cost, time, and complexity to the manufacturing process. Many manufactures provide orientation tabs or other structure on the component to ensure that it is inserted into the conduit in the proper direction.
Therefore, a mixer that reduces streaking and/or does not require an orientation step during assembly is highly desirable.